From 275c5bd0f3317854a00a3cacea4d7d63ac1bce1b Mon Sep 17 00:00:00 2001
From: Luke Parkinson <luke.parkinson@canterbury.ac.nz>
Date: Mon, 25 Nov 2024 13:22:32 +1300
Subject: [PATCH] Create bounding box area calculation process

---
 environment.yml       |  3 ++-
 otakaro/area.py       | 55 +++++++++++++++++++++++++++++++++++++++++++
 otakaro/blueprint.py  |  4 +++-
 terriajs/catalog.json |  7 ++++++
 4 files changed, 67 insertions(+), 2 deletions(-)
 create mode 100644 otakaro/area.py

diff --git a/environment.yml b/environment.yml
index 7f5a9a0e4..026f0d840 100644
--- a/environment.yml
+++ b/environment.yml
@@ -30,7 +30,6 @@ dependencies:
   - botocore>=1.33.10 # Minimum version that is compatible with python >= 3.10 is botocore>=1.13.0
   - scrapy==2.11.1
   - gevent==23.9.1
-  - pywps==4.6.0
   - pip:
     - flask_swagger_ui==4.11.1
     - geovoronoi==0.4.0
@@ -38,5 +37,7 @@ dependencies:
     - celery==5.2.7
     - gunicorn==20.1.0
     - git+https://github.com/LukeParky/NewZeaLiDAR.git@v0.3
+    - pywps==4.6.0 # pywps is available in conda but our fork of OWSLib is required for bounding boxes
+    - git+https://github.com/GeospatialResearch/OWSLib.git
 
 prefix: 
diff --git a/otakaro/area.py b/otakaro/area.py
new file mode 100644
index 000000000..a461fb2a5
--- /dev/null
+++ b/otakaro/area.py
@@ -0,0 +1,55 @@
+# # -*- coding: utf-8 -*-
+"""Defines PyWPS WebProcessingService processes for calculating area of geometries."""
+
+from geopandas import GeoDataFrame
+from pywps import BoundingBoxInput, Process, LiteralOutput, WPSRequest
+from pywps.response.execute import ExecuteResponse
+from shapely import box
+
+
+class BoundingBoxAreaProcess(Process):
+    """Class representing a WebProcessingService process for calculating area of a bounding box"""
+
+    def __init__(self) -> None:
+        """Define inputs and outputs of the WPS process, and assogm process handler."""
+        # Create bounding box WPS inputs.
+        inputs = [BoundingBoxInput('bboxin', 'box in', crss=['epsg:4326'])]
+        # Create area WPS outputs.
+        outputs = [LiteralOutput('area', 'Area', data_type='string')]
+
+        # Initialise the process.
+        super().__init__(
+            self._handler,
+            identifier='area',
+            title="Calculate the area of the polygon.",
+            inputs=inputs,
+            outputs=outputs,
+        )
+
+    @staticmethod
+    def _handler(request: WPSRequest, response: ExecuteResponse) -> None:
+        """
+        Process handler for calculating bounding box area.
+
+        Parameters
+        ----------
+        request : WPSRequest
+            The WPS request, containing input parameters.
+        response : ExecuteResponse
+            The WPS response, containing output data.
+        """
+        # Get coordinates from bounding box input
+        bounding_box_input = request.inputs['bboxin'][0]
+        ymin, xmin = bounding_box_input.ll  # lower left
+        ymax, xmax = bounding_box_input.ur  # upper right
+
+        # Form bounding box into standard shapely.box
+        bounding_box = box(xmin, ymin, xmax, ymax)
+        # Create GeoDataFrame with unit of measurement in metres.
+        gdf = GeoDataFrame(index=[0], crs="epsg:4326", geometry=[bounding_box]).to_crs(epsg=2193)
+
+        # Calculate area in square metres
+        area = gdf.geometry[0].area
+        # Format area
+        display_area = f"{area:.0f} m²"
+        response.outputs['area'].data = display_area
diff --git a/otakaro/blueprint.py b/otakaro/blueprint.py
index e45dac10a..409a59aca 100644
--- a/otakaro/blueprint.py
+++ b/otakaro/blueprint.py
@@ -8,12 +8,14 @@
 
 from src.check_celery_alive import check_celery_alive
 from otakaro import tasks
+from otakaro.area import BoundingBoxAreaProcess
 from otakaro.pollution_model.medusa_process_service import MedusaProcessService
 
 otakaro_blueprint = Blueprint('otakaro', __name__)
 
 processes = [
-    MedusaProcessService()
+    MedusaProcessService(),
+    BoundingBoxAreaProcess(),
 ]
 
 process_descriptor = {process.identifier: process.abstract for process in processes}
diff --git a/terriajs/catalog.json b/terriajs/catalog.json
index ecf452882..3f1e36ceb 100644
--- a/terriajs/catalog.json
+++ b/terriajs/catalog.json
@@ -195,6 +195,13 @@
           "url": "$BACKEND_URL/wps",
           "identifier": "medusa",
           "storeSupported": true
+        },
+        {
+          "type": "wps",
+          "name": "Area",
+          "description": "Calculate the area of the polygon.",
+          "url": "$BACKEND_URL/wps",
+          "identifier": "area"
         }
       ]
     }